Certain congenital deformities and traumatic injuries may result in varying sized and shaped voids in bone. Severe impacts to the head could leave the frontal lobe of the cranium in need of repair, for example. Some catastrophic car accidents, for instance, may leave victims with certain bones of the cranium broken and/or crushed. If enough of the bone is crushed, a surgeon may need to remove fragments of the bone leaving what may be considered a large void in the cranium that needs to be covered and repaired. It is generally difficult to construct or form a single-component prosthesis or implant to span a large and irregularly shaped bone void.
Multiple component implants have been used to cover such bone voids in the cranium, for instance. Multiple component implants for filling voids in bone have utilized butt-type or bevel-type joint designs, for example. Each of these designs generally result in at least some gap remaining between adjacent components after fixation. Fixation members, such as plates and screws, for example, may be added to these designs to secure the engagement between adjacent components and provide rigidity to the assembled construct. Across the joint line; however, these fixation members may be noticeable under the skin and only secure the implant components at specific sites resulting in weaker areas along the joint line where the fixation members are not located.
The aforementioned butt-type and bevel-type may therefore result in uneven loading such that motion and abrasion between adjacent components can occur. Further, uneven loading in a butt-type joint can cause deflection of components in multiple component implants. With bevel-type joints, uneven loading can cause deflection of an inner unsupported component. Further still, there is generally always some degree of gap between adjacent components in either butt-type or bevel-type joints.
Other joints for affixing adjacent components together for filling voids in bone have been used. What may be referred to as a biscuit-type joint, for example, is generally a three-piece joint that requires secondary operations to fabricate. Such joints are generally not preferred over longer joint lengths. Generally, the multiple components used in such joints are difficult to intraoperatively align and assemble.
There exists a need for bone void filling implants having multiple components wherein the components have complementary mating features for providing secure engagement along substantially the entire joint line of the assembled components. Further, there exists a need for such multiple component bone void filling implants to be effectively assembled without the need for the addition of fixation plates and screws along the joint line.